Acute oophoritis and salpingitis were commonly observed in weanling mice injected intraperitoneally with murine pleuropneumonia-like organisms of the catarrhal type (4 strains). Organisms of the injected strain were regularly recovered in cultures from the ovary or uterus during the 3rd to the 5th week but not after the 12th week. They were also obtained from the vagina through the 5th week and with varying results, depending on the strain, from the heart's blood through the 1st week. PPLO injected into the vagina survived for some weeks but did not migrate inwardly nor were they transmitted outwardly to exposed mice. In male mice peritoneal abscesses were sometimes present but the genital organs were normal and free from PPLO. Otitis media, with positive exudate cultures, occurred more often in females and varied in rate with the strain of PPLO. PPLO of the conjunctival type failed to survive in the abdominal cavity of mice and produced no reaction in either the genital or the respiratory tract.